You have been here for 3 years and speak german well - well done! But surely you can understand the Dialekt too by now? Take this opportunity to learn it. You are in Switzerland not Germany, they are entitled to speak the Swiss Dialekt of German, surely? Speaking Hochdeutsch is like speaking a second language for many Swiss, they will do it when asked nicely but it’s a strain. And they rightfully get irritated when it is an expectation by a foreigner living in their country.